The invention concerns the application of substances such as fertilizers, minerals, and/or pesticides according to the specific requirement of an individual section of an area of land in agricultural use.
By making the land application treatment specific to individual sections of land the application rate of fertilizer and pesticides can be automatically adjusted to fit the requirement of the respective section. The following equipment is necessary in order to carry out a section-specific application treatment:                (1) appliances with an electronic control system to adjust the application rate to correspond to a desired value taken from a field map and which depends on the speed of travel and the position in the field operation;        (2) harvesting equipment with devices for recording the local crop yield;        (3) input/output unit (terminal) for the application treatment;        (4) data carrier with desired data for the application treatment and for recording the actual application rate data with corresponding positional association;        (5) navigation equipment (as a rule GPS or DGPS) to determine the position of the vehicle performing the operation;        (6) electronic control system on the tractor for recording and transmitting basic information such as, for example, speed of travel, slippage, engine speed, rpm of power take-off shaft, etc.;        (7) stationary data processing by PC for the application treatment—drawing up the field map of the desired values for the application rate of the substance to be spread; and        (8) additional equipment for determining the local supply of nutrients in the soil, recording the local stock of plants, local climate of the atmosphere and the soil.        
A similar system, in which the electronic controls are connected via a data bus, has been implemented and is already widely available. Known developments point in the direction of adapting the appliance for applying the substances in a manner specific to individual sections of land. As a rule, a specific speed of travel is set for the process, and the application rate is adjusted with the automated control instruments on the appliances according to the speed of travel and the setting established from the application treatment record.
Under these conditions, very costly technology is necessary on each piece of equipment involved in this chain. The extent of the expenditure required can be seen for example from DE 199 43 561 A1, according to which each piece of equipment is provided with final control elements according to its function, with numerous sensors for monitoring the final control elements and with an allocated job calculator. Furthermore as a result of this procedure, when liquid fertilizers or pesticides, for example, are being spread, either only certain methods are possible or else the application no longer meets the actual requirement. Thus, on vehicles for applying liquid manure which have “rebounding plates,” the working width is dependent on the pressure. However, to alter the application rate using the pressure, then inevitably the working width and the accuracy of distribution over the working width will fluctuate. When spraying with pesticides, the application rate is likewise controlled by means of the pressure. However, the distribution of the droplet spectrum alters with the pressure. High pressure results in a higher application rate, but also in a droplet spectrum with very fine drops, so that increased drift and application to the plant stock in deeper layers is no longer possible. Lower pressure results in a lower application rate, but also to a droplet spectrum with large drops and the application to the plants is therefore of inferior quality.
This disadvantage also occurs with fertilizer and lime spreaders driven by a power take-off shaft. Here, the engine speed must be kept constant so that the scatter diagram matches the desired distribution. The application rate is adjusted using a control device on the dosing instrument. At the same time, the equipment compensates for factors influencing the speed of travel, for example slippage.
When spreading liquid manure conventional distribution equipment must be abandoned and correspondingly costly precision distributors provided, so that the distribution over the working width can be independent of the pressure.